Process of and apparatus for comminuting material



Feb. 25, 1930. R. c. NEwHoUsE v 1,748,920

PROCESS OF AND APPARATUSFOR COMMINUTING-MATERIAL Fna Fel.y 2s. 1928Patented Feb. 25, 1930 UNITED STATES PATENT; OFFICE .Y `RAY C/ NEWHOUSE,F MILWAUKEE, WISCONSIN, ASSIGNOR TO ALLIS-CHALMERS MANUFACTURINGCOMPANY, OF MILWAUKEE, WISCONSIN, A CORPORATION 0F y D/ELAWABE PROCESSOF AND APPARATUS FOR COMMINUTING MATERIAL Application led February 23,1928. Serial No. 256,209.

' iict reduced to extremely fine condition. In

an effort to so reduce the material, it has here-v tofore been commoncommercial practice to utilize an air separator to relnove the finematerial from that delivered at the discharge end of atube mill, and toreturn the oversize or coarse material discharged by the air separatorto one of the compartments of the mill for further reduction, The linematerial thus removed by the air separator in accordance with the theprior methods7 constituted the finished product- It has been found,however, that, while the air separator is perhaps the most effectivetype of dry separator for removing fine material from oversize, the mostefficient use of this separator produces a material lacking a sufficientquantity of extremely fine powder, such as is required in high gradecement. It is also well known 4that the capacity of an air separator islfreatly reduced where it is attempted to deliver a very fine product.

In order to -insure production of extremely fine and thoroughlycomminuted cement or the like, the present invention contemplates theprovision of an improved method of reducing the cement forming material,wherein an air separator vor similarly functioning classifying means ismerely employed to prepare' gradedfeed for the fine grinding comminutingcompartment. With thel present improvement, the material which isdelivered @om the air separator merely con; stitutes a feed for and isfurther reduced i-n a comminuting .chamber :provided lwith rela-- tivelysmall tumbling comminuting `bodies whichwi-ll most effectively reducethe fine product. i comminuting bodies employed.

in the fine grinding compartment` in accord-v ance with the presentinvention may be considerably smaller than have heretofore beenconsidered practical, and effectively reducebut with the ungraded feedheretofore used,

it has been necessary to employ comminuting bodies larger than wouldotherwise have been necessary, 'in order to pulverize the largerparticles. In' accordance with the 'present invention, the airseparat-or is not used to prepare a finished product, but, on thecontrary, to prepare a relatively granular material from which the.coarser particles have'been removed, and this relatively granularmaterial is delivered to another compartment containing very smallcomminuting bodies, for final grinding. This also permits operation ofthe air separator at maximum capacity.

Vhile the invention is especially applicable to the manufacture ofcement by a dry process of comminuting, the features thereof aregenerally applicable to the reduction4 of other materials. Although theair separator is especially adapted to classify cement making materialswhen utilizing the dry process of grinding. other forms of classifiersutilizing a'fluid for grading purposes may be effectively employed toattain the improved results herein referred to. The im'- portant featurey,of the invention is the provision of an effective classifier forseparating the vfine material from coarser material deliveietljrom acomminuting chamber, `and the subsequent further reduction ofthe finematerial alone in a comminutorespecially adapted to treat such finematerial.

A clear conception of the several steps constituting the improvedprocess and of one embodiment of apparatus for effecting commercialexploitation thereof, may be had by referring to the drawingaccompanying and forming a part of this y'specification wherein thevarious parts haye been designatedv by suitable reference characters. f

The single figure of thedrawing is a `some'- what diagrammaticillustration of a multiple compartmenttube mill having an air separatorand material transporting devices associated therewith in a manner topermit the improved process to be carried on thereby.

Referring specically to the drawing, the tube mill comprises in generalan elongated drum or shell 5 rotatably supported by means of feed anddischarge end trunnions 6, 7 and having therein partitions which dividethe interior of the shell into successive comminuting chambers 2, 3, 4having tumbling comminuting bodies 26, 27, 28 therein.

The initial or coarse grinding chamber 2 is of larger diameter than theothers, and is provided with a tapered portion 29 at -the discharge endthereof. The feed trunnion 6 at the inlet end of the chamber 2, isprovided with a feeder 9 for introducing the material which is to bereduced. The material after being initially reduced in the chamber 2 bythe large tumbling vcomminuting bodies 26, is delivered through a screen10 constituting a part of the first partition, upon an annular screen 11located externally of the shell 5. The oversize material which fails topass through the screen 11, is returned to the coarse grinding chamber 2by means of return scoops 12, while the separated fine material isdelivered byV gravity to a receptacle 13 located below the The materialdelivered to the receptacle V13 by the screen 11, is removed from this-ber 3 through injection nozzles 36. In the z chamber 3 the material issubjected to the comminuting action of medium size tumbling vcomminutingbodies 27 and is eventually delivered in further reduced conditionthrough an end discharge screen 15 constituting a part of the secondpartition, and subsequently through peripheral openings 16. The materialthus delivered from the intermediate chamber 3 is discharged'by gravityinto a v bucket elevator 17.

The elevator 17 raises the material delivered thereto and finallydischarges the said material through a spout 30.to an air separator 18.The air separator 18 comprises an outer casing having a conical bottom35 formed to receive the separated fine material andto deliver the samethrough a discharge; spout 20 to a stationary receptacle 21 locatedbelow the inlet end of the fine grinding compartment 4. Centrally withinthe outer casing of the air separator, is located a hopper 34 which isadapted to receive the oversize material and to deliver thesame'through' a spout 19 to the stationary receptacle 13, for furthergrindingin the intermediate compartment 3. The material delivered intothe air separator through the spout 30 is deposited upon a rotarydistributor 31 above which is located an air circulating fan 32, boththe fan 32 and the rotor 31 being rotatable at relatively high speed bymeans of driving mechanism 33. As the entering material falls uponwardly and downwardly along the inner surface of the o uter casing. fromthe fan 32 travels downwardly alongl the outer casing, most of theentrained fine As the air delivered material is deposited by gravity anddrops upon the conical bottom 35 from whence it is delivered .to thestationary receptacle 21 as previously described.

The feed end of the fine grinding compartment or chamber 4 is providedwith one or more peripheral spiral scoops 22 which remove the relativelyfine graded material from within the receptacle 21 and, during rotationof the mill, inject the said graded material into 'the inlet end of thechamber 4 through injection nozzles 37. The tumbling comminuting bodies28 withinthe chamber 4 are of relatively small size, sufficient,however, to effectively reduce the graded material admitted to thischamber to a fine powder. The finally comminuted material is eventuallydischarged from the chamber 4 through the end screen 23 into the path ofradially disposed elevating vanes 24 which discharge the final productor powder through the opening 25 vin the discharge. trunnion 7.

As illustrated in the drawing, continuous rotation may be imparted tothe shell '5 by means of' a driving gear 8 located at' the discharge endof the mill.

It will thus be noted that during normal operation of the multiplecompartment tube mill in conjunction with the air separator, thematerial after beingpreliminarily reduced is classified in the airseparator, the

graded relatively line material delivered from '12o the separator beingthe only material treated within the final comminuting chamber 4..

Each of the several compartments 2, 3, 4 is provided with tumblingcomminuting bodies wA 'ch are adapted to effectively reduce the m erialdelivered thereto. In view. of the fact that the fine material removedby the air separator 18 need not be as Aline as' that previouslyrequired, the air separator may be operated at maximum capacitythereby'insuring large production of extremely line ma-I terial at' thedischarge end of the apparatus. While the embodiment of the'inventionspecitically illustrated employs an air separator,

it will be apparent that any similarly funcpersons skilled in the art'.

It is claimed and desired to secure by Letters Patent:

1. The process of comminuting material in a multiple compartment tubemill, which comprises, preliminarily reducing the material in onecompartment of the mill, delivering the preliminarily reduced materialto another compartment of the mill for further reduction, pneumaticallytreating the further reduced material to separate the fine material fromthe oversize, returning said oversize material to a precedingcompartment of the mill for further reduction, and further reducing saidfine material in a subsequent compartment of the mill. f l

2.' The process of comminuting material in a multiple compartment tube.1 mill, byhich comprises, preliminarily reducing the material in onecompartment of themill, delivering the preliminarily reduced material toan- -other compartment of the mill for further reduction, pneumaticallytreating the further reduced material to separate the line materlal fromthe oversize, returning said oversize material to a precedingcompartment of the mill for further reduction together with thepreliminarily reduced material, and further reducing said fine materialin a subsequent compartment of the mill.

3. The process of comminuting ,material in a multiple compartment tubemill, which comprises, preliminarily reducing the material in onecompartment of the mill, delivering the preliminarily reducedmaterial-to a Second compartment of the mil'lfor further reduction,pueumatically treating the ma-Y terial discharged from said secondcompartment to separate the fine mater1al from the oversize, returningsaid oversize material to the inlet end of said second compartment forflrther reduction, and further reducing said ine material in a thirdcompartment of the mill. .c g

4. The process of comminutmg'material in a multiple compartment tubemill, Whlch comprises, preliminarily reducing the material in onecompartment of the mill, deliver ing the preliminarily reducedI materialfrom the mill, returning at least some of the prei liminarily reducedmaterial to a second compartment of the mill for further reduction,

delivering the further reduced material from the mill, pneumaticallytreating thefurther vreduced material to separate the ine mate-.

rial from the oversize, returning the oversize material to said secondcompartment for further reduction together with preliminarily reducedmaterial, and returning said ine material to a. third compartment of themill for further reduction.

5. In combination, a tube mill comprising .I

a shell and partitions dividing said shell into afplurality ofcompartments, and an air separator formed to treat material dischargedfrom an intermediate compartment of said mill to separate the finematerial from the oversize, and vmeans for returning the oversizematerial from said separator to said intermediate compartment and forreturning` said fine material to an end compartment of said mlll forfurther reduction. Y

6. In combination, means forming a series 'of three compartmentsrotatable about an aXis,'the first of said compartments havingrelatively large and heavy freely tumbling comminuting -bodies therein,the second of said compartments having smaller and lighter freelytumbling comminuting bodies therein, and the last of said compartmentshaving still smaller and lighter freely tumbling comminuting bodiestherein, means for feeding to said second compartment material which hasbeen preliminarily reduced in said first compartment, a pneumaticclassiier for separating the fines from the coarse material deliveredfrom said second compartment, and means for delivering said fines aloneto said third compartment for further reduction.

7. In combination, means forming a series of three compartmentsrotatable about an axis, the first of said compartments havingrelatively large and heavy freely tumbling comminuting bodies therein,the second of said compartments having smaller and lighter freelytumbling comminuting bodies therein, and the last of said compartmentshaving still smaller and lighter freely tumbling comminuting bodiestherein, means for feeding to said second compartment-material which has'been preliminarilyreduced in said first compartment, a pneumaticclassilier for separating the fines from the coarse, material deliveredfrom said second compartment, means for `delivering said fines alone tosaid third compartment for further reduction, and means for returningthe coarse material from said classifier to said second compartment forfurther reduction.

8. In combination, a shell rotatable about an axis and forming threesuccessive compartments, the first of said compartments 'being of largerdiameter than the others:

A'lo

'-' preliminary,

alone to said third compartment for further.

reduction.

9. The process of comniinuting material, which comprises, preliminarilyreducing the material by subjecting the same to the impact and abrasiveaction of relatively large and heavy comminuting bodies, further reducing said material by subjecting the same to the action of smaller andlighter'comminuting bodies, pneumatic-ally separating vthe fine from thecoarse product resulting from said further reduction, and finallyreducing the separated fine material alone by subjecting the same to theaction of still ,smaller and lighter comminuting bodies.

10. The process of comminuting material, which comprises, prcliminarilyreducing the material by subjecting the same to the impact and abrasiveaction of relatively large and heavy comminuting bodies, furtherreducing the said material by subjecting the same to the action ofsmaller and lighter comminuting bodies, pneumatically separating thefine from the coarse product resulting from said further reduction,returning the coarse product resulting from said pneumatic separationfor further reduction by said previously mentioned comminuting bodies,4and finally reducing the separated fine material alone by subjectingthe same to the action of said still smaller and lighter comminutingbodies.

11. The process of comminuting material, which comprises,.preliminarilyreducing the material by subjectingthe same to the impact and abrasiveaction of relatively large and heavy comminuting bodies, furtherreducing said material by subjectingthe same to the action of smallerand lighter comminuting bodies, utilizing a fiuid to separate the finefrom the coarse product resulting from said further reduction, -andfinall reducing the separated fine material alone y subjecting the sameto the action of still smaller and lighter comminuting bodies.

12. Apparatus for pulverizing materlal comprising, in combination, amillliavmg a rotary tube, compartments,tberem 1ncludmg intermediate andfinish grind ing compartments, grinding elements in the4 compartments,means lto transfer material from the preliminary compartment to theintei-mediate compartment, an air separator, means to conduct materialfrom the intermediate compartment to the air separator, means to delivertailings from the air separator to the intermediate compartment, andmeans to conduct fines from the separator to the finish grindingcompartment.

13. Apparatus for pulverizing material comprising, in combination, aball tube mill having a rotary tube with compartments therein includingpreliminary, intermediate and finish grinding compartments, ball chargesin the compartments, an air separator, "an elevator for receivingmaterial from the intermediate compartment and for conducting the sameto the air separator, a sump, means to conduct tailings from theairseparator to the sump, scoop means on the tube for transferring materialfrom the sump to the intermediate compartment, a sump adja-v cent thefinish compartment, means to conduct `fines from the air separator tothe latter sump, and scoop means on. the tube for transferring the finesfrom the fines receiving sump to the finish compartment, that they maybe finally reduced therein.

l14. Apparatus for pulverizin, material' comprising, in combination, amill having a rotary tube, compartments therein including preliminary,intermediate and finish grinding compartments, grinding elements in thecompartments, means to transfer material from the preliminarycompartment to the intermediate compartment, an elevator having ahopper, means for discharging material from the intermediate compartmentinto the elevator hopper, an air separator for re' ceiving vmaterialfrom the elevator and for separating the same into fines and tailings,and means to conduct the fines from the air separator to the finishcompartment for final reduction therein.

15. Apparatus for pulverizing material comprising, in combination, amill having a rotary tube, a plurality of compartments in the tube,grinding elements in the compartments, ,an air se arator for receivingmaterial from one'o the compartments and for separating the same intofines and tailings, a sump, means to conduct the tailings from theseparatorl to the sump, a scoop on the tube for transferring thematerial from the sump to one of said compartments, a second sump, meansto conduct fines from the separator to thelatter sum and a scoop onthetube for transferring t e fnesfrom the fines receiving sump tov'theother compartment.

16. Apparatus for pulverizing material comprising, in combination, amill having a rotary tube, preliminary,'intermediate and finishgrindingcompartm ts therein, grindmg elements inthe compartments, adivision head between the preliminary and intermediate compartmentshaving provision for transferring material reduced in the former to thelatter, the tube having a side opening therein for discharging material4from the means to conduct the discharged material to the air separator,a sump for the intermediate compartment, a sump for the finish compart-.ment, means to conduct tailings from/'the air separator to theintermediate compartment sump, means to conduct fines from the separatorto the finish compartment sump,

means to transfer tailings from the inter,

mediate compartment sump into the intermediatecompartment, and means totransfer fines from the finish compartment sump into the iinishcompartment/ 17. Apparatus for pulverizing materials comprising, incombination, a mill having a rotary tube with at least two compartmentstherein and an opening in the tube located between the ends thereof,grinding elements in the compartments, anair separator for receivingmaterial from one of said compartments and for separating the same intofines and tailings, means to conducttailings from the separator to themill and introduce the same through said opening into the tube `,olintoone of said compartments, and means .to conduct fines tothe othercompartment.

18: Apparatus for pulverizing materials comprising, incombination, amill having a rotary tube with compartments `therein inas clndingpreliminary and finish grindin compartments, said tube having openings terein communicating with said compartments and located between the endsofthe tube, grindf ing elements in the compartments, an air separatorfor receiving material from one Ivof said compartments "and forseparating the same into lines and tailings, means to conduct same intones and tailings, means'to conduct the tailings to the mill `for furtherreducfornal reduction, and means to v'deliver the finally reducedmaterial through the end of,

the tubeopposite to the4 feeding-in end Lthereof.`

0 5.- 20. Apparatus for-'pulverizing gmaterialsA intermediatecompartment, an'aii'separator tailings from the separator to the millandv 19. Apparatus for pulverizing materials elements in thecompartments,

tion, means to conduct the lines tothe mill comprising, in combination,a mill having a rotary tube, Aa plurality of compartments iii'rv thetube including a, preliminar finish grinding compartment, grindi7 mentsinthe compartments, Ian air separator for receiving material from one ofthe compartments and for separating the same into fines and tailings, asump, means to conduct partment., grinding elements in the compart-lments, an air separator for receiving material from one of thecompartments and for separatlng the same into fines andv tailings, a

and a v ng elesump, means to conduct the fines from the separator to thesump, and means on the tube for transferring ythe fines from the sum tothe finish grinding compartment for fina reduction therein.

22. Apparatus or -pulverizing materials Y comprising, in combination, amill having a rotary tube with compartments therein; in-

cluding a `finishing compartment, grinding elements in saidcompartments, means in lsaid Itube for transferring material receivingpreliminary reduction in one of said compartments, to anothercompartment for further reductionran air separator, means toconductmaterial from the mill to the air separator, and means to conductmaterial separated by the separator 'simultaneously to said last 'namedcompartment and to said {inishing compartment for further reductiontherein. ,f In testimony whereof, the signature' ofthe inventor is'aiiixed hereto.

RAY o'. imwiioUsE.

I j ofsaid compartments andfor separating the

